Semiconductor chips used in a multitude of electronic devices are composites fabricated from materials including semiconductors, dielectrics, metals, metal oxides, and patterned films. For example, semiconductor chip interconnects require deposition of metals in the feature patterns (e.g., vias) of the chip. Currently, deposition of tantalum films (e.g., tantalum metal, tantalum nitride, and the like) is of interest for preparation of, e.g., diffusion barriers and/or cap layers during semiconductor fabrication.
Various deposition methods are well known in the technical art including, e.g., Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD) also known as Sputter Deposition, and Atomic Layer Deposition (ALD). Tantalum (Ta) precursors based upon the (+5) oxidation state of the tantalum metal have been reported for use in CVD. These organometallic tantalum precursors are selected from the common chemical classes of Ta (V) ethoxides or Ta (V) methoxides and derivatives; Ta (V) pentabromide or Ta (V) pentafluoride and derivatives; and most recently, Ta (V) pentakis dimethylamide compounds have been used. However, these precursors, including the Ta (V) ethoxides and methoxides, are incompatible with next generation solvents (e.g., carbon dioxide), reacting at room or higher temperatures forming undesirable precipitates and/or reaction products. Accordingly, new processes that provide for deposition of tantalum films compatible with next generation solvents are needed.